Rear Window Defogger System Does Not Operate: Description
WARNING: This page is about a different car, the 2006 Lexus GS 430 and 2006 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
When the defogger switch is turned ON, a rear defogger activation request signal is input to the multi-display. Then, the A/C amplifier assembly (A/C ECU) outputs this signal to the defogger relay (Marking: DEFOG) and the rear window defogger system is activated.